Immunoassay has become the method of choice for the quantitation of a large variety of biologically important molecules. Many of the immunoassays utilize a radioactive label. However, because of the inherent problems with using radioactive labels, a number of chemiluminescent and bioluminescent compounds have been used in innumoassay systems as labels on either antigen or antibody. Due to the exothermic nature of chemiluminescent reactions, their quantum yield in general, is very low (&lt;1%) compared to the bioluminescent systems. Ways to enhance the quantum yield of the chemiluminescent reactions are, therefore, desirable.
European Patent No. 0087959 describes an assay utilizing a 6-hydroxy-benzothiazole to enhance the chemiluminescent sensitivity of 2, 3-dihydro-1, 4-phthalazinedione.
U.K. Patent Application GB 2162946A describes the use of certain aromatic amines to enhance the sensitivity of the luminescent reaction of the peroxidase-catalysed oxidation of 2, 3-dihydro-1, 4-phthalazinedione.
In Whitehead et al., "Enhanced Luminescence Procedure for Sensitive Determination of Peroxidase-Labelled Conjugates in Immunoassays," Nature 305, pp 158-159 (1983), the authors describe the use of luciferin in a horseradish-mediated luminol chemiluminescent reaction to increase the chemiluminescent signal.
Prior to the present invention, no procedure was known for enhancing the chemiluminescent signal generated by acridinium esters.
Accordingly it is an object of the present invention to provide a method for the enhancement of the chemiluminescence of acridinium esters.
It is also an object of the invention to provide an enhanced chemiluminescent immunoassay.